WASHINGTON —
Washington is bracing for a major legislative battle this week - not over a specific bill, but over the rules governing the U.S. Senate. The ability of the minority party to block votes, a procedure known as a filibuster, could be curtailed. Weakening the filibuster might stem chronic legislative gridlock, but could also erode a historic American safeguard against the raw will and power of majority rule.

Until recent years, filibustering meant holding the Senate floor and speaking non-stop to prevent a vote, as portrayed by Jimmy Stewart in the 1939 movie Mr. Smith Goes to Washington.

Backers of racial segregation famously - or infamously - filibustered civil-rights legislation in the 1950s and 60s. Earlier this year, Republican Senator Rand Paul held the floor for 13 hours to draw attention to the use of domestic drones.

Most modern filibusters are never seen. A senator files a motion to prevent a vote, and unless a three-fifths supermajority disagrees, the vote is blocked. Once a rare practice, almost all Senate votes of consequence must now overcome a filibuster.

“Is there anybody out there in America that thinks this body is functioning well," asked Majority Leader Harry Reid.

The Nevada Democrat says his party will move to change filibuster rules this week unless Republicans allow confirmation votes on high-profile nominees submitted by President Barack Obama to lead federal agencies. Reid says the ability of the government to function is at stake.

“The constitution gives the president, whoever that president may be, the right and the power to choose his team. It grants the Senate the right to advise and consent on those choices. But consistent and unprecedented obstruction by the Republican caucus has turned ‘advise and consent’ into ‘deny and obstruct’," he said.

Republicans warn of dire consequences for American democracy.

Minority Leader Mitch McConnell said, “That [rules change] would violate every protection of minority rights that have defined the U.S. Senate for as long as anyone can remember. Let me assure you this Pandora’s Box, once opened, will be utilized again and again by future majorities."

In 2005, Democrats were in the minority and defended the filibuster to block judicial nominees submitted by then-President George W. Bush.

“They [Republicans] think the Senate should be a rubber stamp for this president," said Senator Reid at the time.

Then-majority leader Bill Frist accused Democrats of abusing the filibuster and setting a dangerous precedent. “To enshrine new tyranny of the minority into the Senate rules forever," he said.

Changing the Senate rules by a simple majority vote has been dubbed the “nuclear option”, given its potential to forever alter America’s legislative landscape.